From d2bcf55697d2fcdbbc7752779e9d35ff84d8975e Mon Sep 17 00:00:00 2001
From: Matthias Reichl <hias@horus.com>
Date: Sat, 11 Mar 2023 22:41:17 +0100
Subject: [PATCH] drm/vc4: drop unnecessary and harmful HDMI RGB format
 check

RGB is a mandatory format for all DVI and HDMI monitors so there's
no need to check for presence of the DRM_COLOR_FORMAT_RGB444 bit in
color_formats.

More importantly this checks breaks working around EDID issues with
eg video=HDMI-A-1:1024x768D or drm.edid_firmware=edid/1024x768.bin
as the RGB444 bit is only set when a valid EDID with digital bit set in
the input byte is present - which isn't the case when no EDID can be
read from the display device at all or with the in-built kernel EDIDs,
which mimic analog (VGA) displays without the digital bit set.

So drop the check, if we output video on the HDMI connector we can
assume that the display can accept 8bit RGB.

Signed-off-by: Matthias Reichl <hias@horus.com>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 3 ---
 1 file changed, 3 deletions(-)

--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -1962,9 +1962,6 @@ vc4_hdmi_sink_supports_format_bpc(const
 	case VC4_HDMI_OUTPUT_RGB:
 		drm_dbg(dev, "RGB Format, checking the constraints.\n");
 
-		if (!(info->color_formats & DRM_COLOR_FORMAT_RGB444))
-			return false;
-
 		if (bpc == 10 && !(info->edid_hdmi_rgb444_dc_modes & DRM_EDID_HDMI_DC_30)) {
 			drm_dbg(dev, "10 BPC but sink doesn't support Deep Color 30.\n");
 			return false;
